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US5454051A
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Method of reducing block artifacts created by block transform compression algorithms
Assignee: Eastman Kodak Co
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Filing: 1991-08-05
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Granted: 1995-09-26
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Expires: 2011-08-05
Abstract
Abstract A method of improving image quality when using block transform image compression algorithms by applying a variable lowpass filter (blur) operation on block boundaries that is based on the coefficients of the transformed data. The method of reducing block artifacts results from adaptively blurring the block boundaries based on the frequency content of the blocks. Low frequency blocks are heavily blurred, while high frequency blocks should have very little blur.
Inventors
- 👤 Craig M. Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 08:27
CPC Classifications
G; G06; G06T; G06T5/00; G06T5/70; G06T5/20; H; H04; H04N; H04N19/00; H04N19/10; H04N19/102; H04N19/124; H04N19/126; H04N19/50; H04N19/503; H04N19/51; H04N19/527; H04N19/85; H04N19/86; G06T2207/00; G06T2207/20; G06T2207/20004; G06T2207/20012; G06T2207/20172; G06T2207/20192; H04N19/60
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
111 words
A method for decoding compressed image data using block transformed images wherein block boundaries are adaptively processed to reduce block artifacts in it reconstructed image, comprising the steps of: decoding the compressed image data to create transform coefficients; applying an inverse transform to the transform coefficients obtained from the compressed image data; frequency analyzing the transform coefficients to determine a frequency content of the transformed image along boundaries between blocks; adjusting a strength of a low pass blur filter in response to the analyzed frequency content of the transformed image along the block boundaries; and processing the transform coefficients with said filter to reduce block artifacts along the boundaries between blocks.
Claim 2
Independent Claim
111 words
A method for decoding compressed image data using block transformed images wherein block boundaries are adaptively processed to reduce block artifacts in it reconstructed image, comprising the steps of: decoding the compressed image data to create transform coefficients; applying an inverse transform to the transform coefficients obtained from the compressed image data; frequency analyzing the transform coefficients to determine a frequency content of the transformed image along boundaries between blocks; adjusting a strength of a low pass blur filter in response to the analyzed frequency content of the transformed image along the block boundaries; and processing the transform coefficients with said filter to reduce block artifacts along the boundaries between blocks.
Claim 3
Dependent Claim
15 words
The method set forth in claim 1 wherein the transform is a Discrete Cosine function.
Claim 4
Dependent Claim
17 words
The method set forth in claim 1 wherein the transform takes the form of a Fourier transform.
Claim 5
Dependent Claim
17 words
The method set forth in claim 1 wherein the transform takes the form of a Hadamard transform.
Claim 6
Dependent Claim
17 words
The method set forth in claim 1 wherein the transform takes the form of a Harr transform.
Claim 7
Independent Claim
89 words
A method for decoding compressed image data using block transforms that subdivide an image into blocks of pixels, comprising the steps of: decoding the compressed image data to create a block of transform coefficients; applying a bidirectional transformation to the block of transform coefficients; transmitting the transform coefficients for blur control; adjusting an amount of blur in a low pass filter along adjacent block boundaries in response to the transform coefficients; and processing the transmitted transform coefficients with said filter to reduce block artifacts along the boundary between blocks.
Claim 8
Independent Claim
89 words
A method for decoding compressed image data using block transforms that subdivide an image into blocks of pixels, comprising the steps of: decoding the compressed image data to create a block of transform coefficients; applying a bidirectional transformation to the block of transform coefficients; transmitting the transform coefficients for blur control; adjusting an amount of blur in a low pass filter along adjacent block boundaries in response to the transform coefficients; and processing the transmitted transform coefficients with said filter to reduce block artifacts along the boundary between blocks.
Claim 9
Independent Claim
107 words
A method for decoding compressed image data using block transforms that subdivide each image into blocks of pixels, comprising the steps of: reading the compressed image data; decoding the compressed image data to create a block of transform coefficients; applying an inverse transform to said block of transform coefficients to provide a block of reconstructed image data; analyzing the block of transform coefficients to determine a level of activity in said block of transform coefficients; adjusting blur in a variable strength blur filter based upon said activity; and processing the blocks of reconstructed image data with said filter to reduce block artifacts along a boundary between blocks.
Claim 10
Independent Claim
107 words
A method for decoding compressed image data using block transforms that subdivide each image into blocks of pixels, comprising the steps of: reading the compressed image data; decoding the compressed image data to create a block of transform coefficients; applying an inverse transform to said block of transform coefficients to provide a block of reconstructed image data; analyzing the block of transform coefficients to determine a level of activity in said block of transform coefficients; adjusting blur in a variable strength blur filter based upon said activity; and processing the blocks of reconstructed image data with said filter to reduce block artifacts along a boundary between blocks.
Claim 11
Dependent Claim
15 words
The method set forth in claim 7 wherein the transform is a Discrete Cosine function.
Claim 12
Dependent Claim
17 words
The method set forth in claim 7 wherein the transform takes the form of a Fourier transform.
Claim 13
Dependent Claim
17 words
The method set forth in claim 7 wherein the transform takes the form of a Hadamard transform.
Claim 14
Dependent Claim
17 words
The method set forth in claim 7 wherein the transform takes the form of a Harr transform.
Claim 15
Independent Claim
102 words
An apparatus for decoding compressed image data using a block transformation that subdivides each image into blocks of pixels, comprising: means for decoding the compressed image data to provide decoded transform coefficients; a low pass blur filter; means for applying an inverse transform to the transfer coefficients to provide a decompressed image signal to said low pass blur filter; means for analyzing a frequency of the decoded transform coefficients; and means for adjusting an amount of blur in said low pass blur filter in accordance with the analyzed frequency content of the decoded transform coefficients reducing block artifacts along adjacent block boundaries.
Claim 16
Independent Claim
102 words
An apparatus for decoding compressed image data using a block transformation that subdivides each image into blocks of pixels, comprising: means for decoding the compressed image data to provide decoded transform coefficients; a low pass blur filter; means for applying an inverse transform to the transfer coefficients to provide a decompressed image signal to said low pass blur filter; means for analyzing a frequency of the decoded transform coefficients; and means for adjusting an amount of blur in said low pass blur filter in accordance with the analyzed frequency content of the decoded transform coefficients reducing block artifacts along adjacent block boundaries.
Claim 17
Dependent Claim
14 words
The apparatus set forth in claim 12 wherein the transform is a Discrete Cosine.
Claim 18
Dependent Claim
17 words
The apparatus set forth in claim 12 wherein the transform takes the form of a Fourier transform.
Claim 19
Dependent Claim
17 words
The apparatus set forth in claim 12 wherein the transform takes the form of a Hadamard transform.
Claim 20
Dependent Claim
17 words
The apparatus set forth in claim 12 wherein the transform takes the form of a Harr transform.
Claim 21
Independent Claim
133 words
An apparatus for decoding compressed image data using a block transformation that subdivides each image into blocks of pixels, comprising: means for reading the compressed image data; means for decoding the compressed image data from said means for reading to create blocks of transform coefficients; means for applying an inverse transform to the blocks of transform coefficients resulting in blocks of reconstructed image data; means for analyzing the blocks of transform coefficients to determine an activity level in the blocks of transform coefficients; a variable strength blur filter receiving said to receive the blocks of reconstructed image data; and means for setting a blur level of said variable strength blur filter based upon the activity level of the blocks of transform coefficients reducing block artifacts along a boundary between the blocks of pixels.
Claim 22
Independent Claim
133 words
An apparatus for decoding compressed image data using a block transformation that subdivides each image into blocks of pixels, comprising: means for reading the compressed image data; means for decoding the compressed image data from said means for reading to create blocks of transform coefficients; means for applying an inverse transform to the blocks of transform coefficients resulting in blocks of reconstructed image data; means for analyzing the blocks of transform coefficients to determine an activity level in the blocks of transform coefficients; a variable strength blur filter receiving said to receive the blocks of reconstructed image data; and means for setting a blur level of said variable strength blur filter based upon the activity level of the blocks of transform coefficients reducing block artifacts along a boundary between the blocks of pixels.
Claim 23
Dependent Claim
14 words
The apparatus set forth in claim 17 wherein the transform is a Discrete Cosine.
Claim 24
Dependent Claim
17 words
The apparatus set forth in claim 17 wherein the transform takes the form of a Fourier transform.
Claim 25
Dependent Claim
17 words
The apparatus set forth in claim 17 wherein the transform takes the form of a Hadamard transform.
Claim 26
Dependent Claim
17 words
The apparatus set forth in claim 17 wherein the transform takes the form of a Harr transform.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-09-25 | 1999-03-27 | 1999-09-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-09-25 | 2003-03-27 | 2003-09-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-09-25 | 2007-03-27 | 2007-09-26 | $7700.00 | Window Closed / Lapsed |